It depends a lot on how hard you are pushing as well as the setting. I guess you are putting in quite a bit if you have it on Eco. It's pretty common that 'real life' use of an electric bike even on moderate power settings is around 1/3 what is quoted as 'up to' figures (light rider, flat road, perfect conditions, minimum assist). 30 miles or less is a fairly reasonable range for that bike in winter with some significant hills.
You'll probably find the gauge is far from linear; and might have quite a long way on 'full', and may give you a bit extra near 'empty'. Also, it's probably based on battery voltage (which drops from 42v full to around 30v empty). Voltage sags quite a bit as you climb hills or otherwise tax the motor, and then recovers again as you ease off, so the gauge may well drop a bar or two on hills and recover.
Check
https://www.bosch-ebike.com/en/service/range-assistant/ and play with some of the variables. Not directly applicable to your bike, but the differences from different conditions will be similar, and with a little interpretation you should be able to get a good idea of yours. You'll see with a 400 battery (about your size) it can give figures of 100 miles even on Tour setting if you make everything else easy, speed up a bit and change to hilly winter and it drops below 50, add realistic weight another drop to 33, city bike and tyres to 23 miles. So that's four times difference even with the same assist level and without going to really hilly.